Clinical applications of bone density testing for osteoporosis.

Bone mineral density (BMD) testing is a clinical tool to diagnose osteoporosis or low bone density, predict fracture risk, and monitor changes in bone density over time. Non-invasive measurement of BMD is done with a variety of technologies for many different skeletal sites. Dual-energy X-ray absorptiometry (DXA) is the gold-standard for diagnosing osteoporosis and monitoring changes in BMD over time. Optimal use of DXA requires staff training and standard operating procedures that include quality controls for instrument maintenance, patient education, indications and contraindications for testing, precision assessment, scan acquisition, analysis, interpretation, and reporting. Other technologies, as well as DXA, are used to estimate the risk of fracture. BMD is commonly expressed as a T-score, the standard deviation variance of the patient's BMD compared to a young-normal reference population. In untreated postmenopausal women, there is a strong correlation between T-score and fracture risk, with fracture risk increasing about two-fold for every standard deviation decrease in bone density. BMD in postmenopausal women is classified as normal, osteopenia, or osteoporosis according to criteria established by the World Health Organization. BMD testing, combined with assessment of clinical risk factors for fracture, allows healthcare providers to identify patients who may benefit from pharmacologic therapy to reduce the risk of future fractures. Clinical applications of BMD testing are presented in this review.